Celiac disease, also called celiac sprue or gluten-sensitive enteropathy, is a disease which develops in susceptible individuals in response to the intake of dietary gluten. The disease is caused by an immune reaction to gluten, most noticeably, to gliadin-derived peptides. These peptides elicit an immune response damaging microvilli which are tiny protrusions that line the small intestine. Their destruction causes malabsorption of nutrients leading to a variety of generalized gastro-intestinal disease symptoms such as diarrhea and abdominal pain. Additional and secondary symptoms include weight loss, fatigue, anemia, osteopenia and skin and tooth enamel defects.
A related disease is dermatitis herpetiformis, which is a chronic eruption characterized by clusters of intensely pruritic vesicles, papules, and urticaria-like lesions. IgA deposits occur in almost all normal-appearing and perilesional skin. Asymptomatic gluten-sensitive enteropathy is found in 75 to 90% of these patients and in some of their relatives. Onset is usually gradual. Itching and burning are severe, and scratching often obscures the primary lesions with eczematization of nearby skin, leading to an erroneous diagnosis of eczema. Strict adherence to a gluten-free diet for prolonged periods may control the disease in some patients, obviating or reducing the requirement for drug therapy. Dapsone, sulfapyridine and colchicines are sometimes prescribed for relief of itching.
Gluten allergy and gluten intolerance are related ailments which result from an overreaction of a subject's immune system to gluten and gliadin that are normally considered harmless. The symptoms are very similar to celiac sprue or gluten-sensitive enteropathy but without the enteropathy. Afflicted subjects have an abundance of IgG and IgA antibodies against α/β-gliadin. Typical symptoms are abdominal pain, gas, bloating and diarrhea; there is a general feeling of sickness and fatigue after grain-based products are consumed. Severe allergy can led to Gluten-sensitive idiopathic neuropathy where the typical symptoms are ataxia and peripheral neuropathies because the primary tissue targeted are the central nervous system and peripheral nerves.
There is currently no good marketed treatment for celiac disease or the various gluten and gliadin allergy related diseases. In most cases, the symptoms are reversible and can be avoided if the patients refrain from the intake of gluten. Complete elimination of gluten from the diet is not easy to achieve and maintain. Glutens are abundantly contained in dietary products made of wheat, barley and rye. Moreover, gluten is also widely used, for example in commercial soups, sauces, ice creams, hot dogs, and other foods, that patients need detailed lists of foodstuffs to avoid and expert advice from a dietitian familiar with celiac disease. Ingesting even small amounts of gluten may prevent remission or induce relapse. Supplementary vitamins, minerals, and hematinics may also be required, depending on deficiency. A few patients respond poorly or not at all to gluten withdrawal, either because the diagnosis is incorrect or because the disease is refractory. In the latter case, oral corticosteroids (e.g., prednisone 10 to 20 mg bid) may induce response.
The gluten-free diet advice is to be followed for a lifetime, and intake of gluten, even in small amounts, can cause an immediate immunological response. In view of the serious and widespread nature of Celiac Sprue, the development of a non-dietary therapy would allow patients to lead a more normal life and find a broad application in the gluten-sensitive patient population. The present invention addresses such needs.
Current approaches geared towards the development of treatment options for celiac disease and allergic gluten sensitivity focus on enzyme preparations that are able to digest the immunogenic gluten/gliadin oligopeptides into smaller fragments that do not elicit an immune response. Gluten proteins are remarkably resistant to digestive enzymes operating in the gastro-intestinal tract due to the low content of lysine/arginine and the high proline content. Enzymes capable of gluten digestion are considered an attractive therapeutic option.